Inductive device for detecting the passage of railway vehicles



June 30, 1936. w, acy- A E 7 2,045,923

INDUCTIVE DEVICE FOR DETECTING THE PASSAGE OF RAILWAY VEHICLES FiledJan. 15, 1955 IMLZVT ATTORNE'Y Patented June 30, 1936 INDUCTIVE DEVICEFOR DETECTING THE PASSAGE OF RAILWAY VEHICLES Wade H. Reichard,Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application January 15, 1935, Serial No. 1,923

6 Claims.

This invention relates to a device responsive to the passage of railwayvehicles, and more particularly to such a device of the inductive typeoperated by the wheels of the vehicle.

In the art of railway signalling, in connection with the control ofhighway crossing signals and withvarious other types of apparatus andsystems, it is sometimes desirable to detect the presence or passage ofa railway vehicle or train 10 without employing the well known trackcircuit operated by a wheel shunt; and in accordance with thisinvention, generally speaking, it is proposed to provide a. device whichis inductively responsive to the presence of a wheel of a railway 15vehicle without physical contact or mechanical impact of engaging parts,said device operating to open or close contacts for any desired controlpurpose.

Various characteristic features, attributes, and 20 advantages of theinvention will be in part apparent, and in part explained as thedescription progresses.

In the accompanying drawing, Fig. 1 is a plan view showingdiagrammatically one specific or- 25 ganization of parts in accordancewith this invention; and Fig. 2 is an end View illustrating thedisposition of the cores with respect to a track rail.

Generally speaking, the inductive device em- 30 bodying this inventioncomprises two coils or windings, conveniently termed primary andsecondary coils, which are inductively coupled and preferably mounted onlaminated iron cores, the

, primary coil being energized with alternating 3 current and thesecondary coil being connected to a relay or other electro-responsivedevice, said coils being disposed in such a way with respect to a trackrail that the wheel of a vehicle weakens the lnductive coupling betweensaid coils and causes de-energization of the relay.

In the specific form of the invention illustrated, two laminated ironcores l and 2 are disposed on opposite sides of the usual track rail T.On one core I is the primary coil P, and on the other core 2 thesecondary coil S. The upper edges of these cores l and 2 are located asfar above the upper face of the track rail as clearances will permit, asfor example about 2"; 50 and these cores are preferably tilted as shownin Fig. 2 to keep the coils P and S below the upper edges of the cores,the laminations being stepped or staggered to keep the pole faces ofthese cores substantially vertical. These cores I and 2, and 56 thecoils P and S, are supported and housed in a suitable non-magneticcasing fastened to the ties, as indicated by dotted lines in Fig. 2.

The primary coil P is connected to a suitable source of alternatingcurrent, preferably of a relatively higher frequency such as 180 cycles.5 As illustrated, the primary coil P is connected to the secondary of atransformer 3, the primary of which is energized from a suitable source,as the generator 4. The primary circuit also includes a condenser 5,preferably having its capacity adjustable in a suitable manner as by thep-roviison of taps; and this condenser 5 is set with a device in placeto make the primary circuit substantially resonant.

The secondary coil S is connected to a suitable electro-responsivedevice or relay R. As shown, this relay R. is assumed to be of theconventional direct current tractive type, and is connected to thecircuit of the secondary coil S through a double wave rectifier 6 of theusual and well-known construction. The circuit for the secondary coil Sis made resonant by an adjustable condenser I.

When no car is present, sufiicient energy is transferred from theprimary P to the secondary coil S through the inductive coupling toenergize the relay R.

When a car wheel W passes between the pole faces of the cores l and 2,as indicated by dotted lines, the normal magnetic coupling between theprimary coil P and secondary coil S is reduced, and the relay R. isde-energized. This operation is attributed to the fact that the carwheel being magnetic, tends to shunt the primary flux from thesecondary, and also to the fact that, since the Wheel is both metallicand magnetic, the inductive reactance and effective resistance in boththe primary and secondary circuits are materially changed, therebydetuning both of these circuits to reduce the primary current and thusthe voltage induced in the secondary coil, and also decreasing thecurrent in the secondary circuit that would otherwise be produced by thesame induced voltage.

Since the ends of the cores l and 2 are above the top of the track rail,the presence of the car wheel can materially reduce the transfer ofenergy from the primary P to the secondary coil S, even though the trackrail T is of the usual magnetic material; but if desired, a non-magneticsection of the track rail of manganese steel or the like, may be used atthose places where the inductive device of this invention is to belocated, so that the car wheel will produce a greater effeet. 56

It will be noted that the relay R is normally energized, and thatfailure of the source of current, or breaking of wires, will be on theside of safety.

In the arrangement shown, the relay R is deenergized when the car wheelcomes within the controlling range of the device, and is again energizedas soon as the car wheel passes beyond this range; but in certainapplications or uses, it may be desirable to make the relay R a stickrelay, so that when once de-energized by the passage of the car wheel,it remains de-energized until otherwise restored.

While the relay R is shown as a direct current relay of the usual typeof construction energized through a rectifier, a device directlyoperated by alternating current may be employed, preferably a relay ofthe tractive armature type, such as disclosed in my prior Patent No.1,785,703, December 16, 1936.

No attempt has been made to disclose any particular application or useof the inductive device of this invention, either for the control ofhighway crossing signals, for wheel counting purposes or the like, suchapplications and uses being readily appreciated by one skilled in theart. Also, various adaptations, modifications, and additions may be madein the particular structural organization illustrated, without departingfrom the principles and functions of the invention.

What I claim is:

l. A device responsive to the passage of railway vehicles comprisinginductively coupled primary and secondary coils disposed in positionrelative to a track rail to have their coupling reduced by the presenceof a vehicle wheel, means for energizing the primary coil withalternating current, and electro-responsive means connected to thesecondary coil.

2. A device responsive to the passage of railway vehicles comprisinginductively coupled primary and secondary coils disposed in positionrelative to a track rail to have their coupling reduced by the presenceof a vehicle wheel, said primary coil being included in a circuitsupplied with alternating current and tuned to resonance, andelectro-responsive means connected to the secondary coil.

3. In a device of the type described, magnetic cores constitutingpartial magnetic circuits and disposed on opposite sides of the trackrail in position to have their polar ends bridged by a vehicle wheel,primary and secondary coils on the respective cores, said primary coilbeing energized with alternating current, and an electro-responsivedevice connected to the secondary coil.

4. An inductive device for detecting the presence of a vehicle wheel ona railway track comprising, inductively coupled primary and secondarycircuits having portions thereof disposed in position relative to thetrack rail to have their coupling reduced by the presence of the vehiclewheel, means for energizing the primary circuit with alternatingcurrent, said primary and secondary circuits being both resonant at thefrequency of said alternating current, and electroresponsive meansconnected to the secondary circuit.

5. An inductive device for detecting the presence of railway vehiclescomprising, magnetic cores disposed on opposite sides of the track railin position to have their ends bridged by a vehicle wheel, a primarycoil on one of said cores included in a resonant circuit supplied withalternating current, a secondary coil on the other core included in aresonant circuit, said secondary circuit including a double-waverectifier, and a relay connected to said rectifier.

6. An presence of railway vehicles comprising, separate U-shapedmagnetic cores disposed on opposite sides of the track rail with theiropen ends positioned above the rail and in position to have their endsbridged by a vehicle Wheel, a primary coil on one of said cores includedin a resonant circuit supplied with alternating current, a secondarycoil on the other core included in a resonant circuit, and a relayconnected to the circuit of the secondary coil.

WADE H. REICHARD.

inductive device for detecting the

